GLACIATION IN THE TELLURIDE QUADRANGLE — 733 
AGE OF THE DRIFT 
1. More recent epoch.—The age of the more recent deposits of 
drift is to be regarded as the same, in general, as that of the deposits 
of the Late Wisconsin stage of the continental ice sheet which 
covered the northern part of North America in Pleistocene time. 
It is evident, however, that the ice persisted in the upper parts of 
valleys until within very recent time, as shown by the crevassed 
névé ice reported a few years ago from the northern part of the 
quadrangle,‘ and by the signs of recent glacial movement seen in the 
rock streams, previously described in this paper. While correlated 
with the Wisconsin stage of the continental glacier, it is for the 
reasons just given to be understood that glacial ice remained in the 
quadrangle for a very considerable period after the continental ice 
sheet had disappeared from the northern part of the United States 
east of the Mississippi River. : 
2. Earlier epoch or epochs.—In considering the age of the earlier 
drift deposits it is to be observed that the drift referred to an earlier 
epoch or to earlier epochs of glaciation may be grouped as to position 
in two classes, viz.: (1) that found frequently on the tops of mesas 
or ridges, sometimes on slopes, at elevations ranging up to 500 feet 
above the upper limit of the nearest glacial deposits of the more 
recent epoch, and at distances ranging up to one and one-half miles 
beyond the edge of the more recent deposits; and (2) that found in 
valleys whose upper portions lack the usual evidences of recent 
glaciation. 
It is to be understood that in grouping together certain deposits 
under the common name of earlier drift, no assertion is made as to 
the age of the respective deposits with reference to each other. 
From a consideration of the position of the two classes of deposits 
named above, however, the inference is clear that the amount of 
erosion since (1) was deposited has been very great, while the 
amount of erosion since (2) was deposited is comparatively small. 
It is, therefore, certain that all of the deposits classed as earlier 
drift are not of thesame age. But the evidence afforded by deposits 
in the Telluride quadrangle is not sufficient to warrant the con- 
clusion that three distinct glacial epochs are to be recognized. It 
t Cross, Telluride Folio, p. 15. 
